| Project/Area Number |
07457008
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General physiology
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| Research Institution | CHIBA UNIVERSITY |
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Principal Investigator |
FUKUDA Yasuichiro CHIBA UNIVERSITY,SCHOOL OF MEDICINE,PROFESSOR, 医学部, 教授 (10009649)
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| Co-Investigator(Kenkyū-buntansha) |
SUDO Tomoko CHIBA UNIVERSITY,SCHOOL OF MEDICINE,ASSISTANT, 医学部, 助手 (20272320)
HAYASHI Fumiaki CHIBA UNIVERSITY,SCHOOL OF MEDICINE,Lecturer, 医学部, 講師 (80173029)
CHIBA Tanemichi CHIBA UNIVERSITY,SCHOOL OF MEDICINE,PROFESSOR, 医学部, 教授 (20009525)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥5,200,000 (Direct Cost: ¥5,200,000)
Fiscal Year 1996: ¥1,500,000 (Direct Cost: ¥1,500,000)
Fiscal Year 1995: ¥3,700,000 (Direct Cost: ¥3,700,000)
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| Keywords | Respiratory rhythm / CO2 / Oxygen / Rostral-ventral medulla / Inspiratory activity / Brain slice / Glossopharyngeal nerve / Phrenic nerve / 延髄 / 脳切片 / 新生ラット / 若年成熟ラット |
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| Research Abstract |
The respiratory rhythm is generated in the medulla oblongata when proper extracellular fluid environments such as normal carbon dioxide and oxygen partial pressure are maintained. However, possible roles and mechanism of action of carbon dioxide and oxygen in the generation of respiratory rhythmicity are still unknown and controversial. The present study aims to determine these items using anesthetized rats in vivo preparation together with isolated in vitro coronary slice preparations obtained from the rat medulla oblongata. The inspiratory discharge profiles of the glossopharyngeal nerve (stylopharyngeal muscle branch, IX) are recorded as an appropriate index of generating neural inspiratory outputs from medullary center. The generation of inspiratory output is composed of two processes, the first, basic rhythmic inspiratory activity with slow onset which appears in the early onset of IX inspiratory discharges and the second, synchronized inspiratory bursts appearing in many respiratory nerves such as phrenic nerve. The reduction of arterial Pco_2 inhibited the second process resulting in the decrease in inspiratory synchronized bursts and then the first process causing the reduction of respiratory frequency. In peripheral chemodenervated rats, the reduction in arterial Po2 induced preferential decrease in respiratory frequency. In the isolated medullary slice of new born and young adult rats, the reduction in Pco_2 decreased the frequency of spontaneous rhythmic bursts of neurons locating in the rostral-ventral medulla
These results suggest that the rhythmic respiratory outputs are generated via two processes, i.e., 1) spontaneous rhythmic inspiratory activity of rostral-ventral medullary neurons of primary importance, and 2) synchronization of inspiratory activity in many respiratory output neurons which receive rhythmic signals from 1) neuronal substrates, and that CO2 act both 1) and 2) whereas hypoxia directly acts on 1) process.
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